Strain Sensors in Wearable Devices

Abstract

Abstract. This chapter discusses the use of strain sensors in wearable devices. Strain sensors are used to monitor deformation under applied load. Various techniques for the fabrication of strain sensors are discussed and some example applications are presented. Special focus is placed on textile based and inkjet-printed strain sensors. Textile based strain sensors open new frontiers for wearable systems by integrating sensors into garments which can be used for extended periods of time. Inkjet printing along with conductive inkjet inks provides low cost, efficient, and rapid prototyping solution for implementation of strain sensors in wearable devices. Applications in the area of remote monitoring of physiological signals, vital signs, and human activity are presented.

Preferred Placement and Usability of a Smart Textile System vs. Inertial Measurement Units for Activity Monitoring

“…Despite the fact that a number of STSs have been developed to monitor physiological factors and activities [ 1 , 32 , 35 , 72 ], they are by no means exhaustive in terms of the data they are capable of capturing. For example, there is currently no type of STS that can directly measure acceleration and velocity.…”

“…Sensor: A smart textile sensor is a sensitive fiber, yarn, or fabric that transduces an external stimulus (e.g., physical or chemical) [ 27 , 29 , 30 , 31 , 32 ]. Pressure, temperature, heart rates, optical parameters, and muscle strain are several examples of features that smart textile sensors can measure [ 27 , 29 , 31 , 32 , 33 , 34 , 35 , 36 ].…”

Wearable strain sensors: state-of-the-art and future applications

“…Such materials can sense mechanical strain by the electron tunneling effect between adjacent particles or by sensing the resistance change due to the opening and closing of microcracks by mechanical deformation. [43][44][45][46][47][48][49][50] These schemes have shown more extensive strain sensing ranges with similar gauge factors compared to rigid materials. Furthermore, they can be integrated into textiles with low manufacturing costs.…”

Body Area Networks in Healthcare: A Brief State of the Art

“…Therefore, they can be used to detect the movement of a joint in a human body. Usually, these kinds of sensors are formed by a thin film conductor on a silicone elastomer [21]. The small size allows for mounting strain sensors on the human body to detect motion like the bending of an elbow or knee.…”